Today in the digital era, as digital television and digital signal processing technology progresses, digital television programs and high definition televisions have become a mainstream. Considering traditional television signals transmitted by cable or wireless means, the signals are transmitted as analog signals. Therefore, noises are accumulated along the transmission path to undesirably affect play quality. In contrast, the noise issue may be avoided when using digital signal transmission. Not only the signal clarity is maintained, but also a higher volume of data can be carried on a same channel by compressing and encoding the data. Further, digital signal transmission also allows implementation of more signal processing methods.
FIG. 1 is a schematic functional block diagram of a conventional digital television 100. Referring to FIG. 1, via a channel tuner 102, a digital television 100 receives television signals generated by a television signal source 101. After being processed by a demodulator 103 and a demultiplexer 104, the television signals are decoded by an audio decoder 111, a video decoder 112 and a data decoder 113. Audio data is played on a speaker 131, and video data is displayed on a display panel 132 after being processed by a graphics processor 121.
The television signals input from the television signal source 101 are first decoded by the data decoder 113 and then sent to a central processing unit 122 for further processing. By operating a control interface 140 including a remote controller 141 and panel buttons 142 on the digital television, user-specified setting information of various functions is processed by the central processing unit 122, and then stored and recorded in a system memory 150. The system memory 150 comprises a dynamic random access memory (DRAM) 151, a flash memory 152, and an electrically erasable programmable read-only memory (EEPROM) 153.
Information associated with the foregoing television signals including number of channels, channel frequencies, channel identification codes, channel program titles, channel program ratings and channel sequence, as well as an electronic programming guide (EPG) and interactive information, is generally referred as channel information. For example, the digital television 100 is set to perform autoscan on the received television signals, and the display panel 132 displays corresponding information of the autoscan result such as the number and sequence of channels. That is, the number of channels of cabled and wireless programs, and corresponding video and audio channels, is obtained. Based on the channel identification code, the central processing unit 122 combines corresponding video and audio channels using the channel identification code so as to display a complete television program. For example, a video channel, or a visual channel, may correspond to several audio channels, or sound channels such as in different language versions of English, French, and Spanish. Updates and records of the information are stored in the system memory 150 for the user's future reference.
The foregoing setting information associated with functions of the user control interface 140 include contrast, brightness and chromaticity of images on the digital television 100, or volume adjustment, display language, special channel lock, information display such as whether to enable display of channel number and time, menu language, sleep timer, no-signal mute, and full blue screen. All the above setting information is called on-screen display (OSD) setting information. For example, while viewing the program, a user is allowed to set audio and video conditions for the speaker 131 and the display panel 132, respectively, and to save the setting information in the system memory 150. Thus, settings of the stored setting information are applicable to other channels switched from an original channel, as well as to channels after again turning on the digital television 100 that is previously turned off with previous audio and display conditions.
According to current technologies, the DRAM 151 of the system memory 150 serves as a register for temporary information storage, and the flash memory 152 is used for recording operating program codes or firmware. Above-mentioned information including settings of channel information and OSD setting information is recorded in the EEPROM 153. Therefore, memory units provided in a conventional digital television set are utilized with designated functions.
The EEPROM 153 indeed provides the function of recording and updating of the setting information of a digital television, and data access of the EEPROM 153 is completed by direct data writing without needing an extra step of clearing the memory, thus speeding up the information recording and update. However, the EEPROM 153 generally has a higher cost. In addition, using several memory units in a digital television set complicates the circuit design. There is a need for an alternative solution of a memory unit for recording and updating the setting information such that the product cost as well as complications of circuit design is reduced.
Accordingly, the primary object of the present invention is to provide an apparatus with lower product cost while attaining the same functions.